Simplified cell location information sharing for positioning purposes

ABSTRACT

Disclosed are techniques to determine a position of a user equipment (UE). In an aspect, the UE receives a plurality of positioning reference signals (PRS) from a plurality of cells. The UE determines a plurality of time of arrivals (TOA) of the plurality of PRSs, and prunes the plurality of TOAs based on the plurality of PRSs. The UE then derives a time difference of arrival (TDOA) vector from the pruned TOAs. The TDOA vector includes multiple TOA related measurements of multiple cells. The UE prunes the TOAs such that the cells represented in the TDOA vector are sufficiently geographically dispersed to determine the position of the UE at least in 2D.

CROSS-REFERENCE TO RELATED APPLICATION

The present application for patent claims priority under 35 U.S.C. § 119to Greek Patent Application No. 20180100460, entitled “SIMPLIFIED CELLLOCATION INFORMATION SHARING FOR POSITIONING PURPOSES,” filed Oct. 5,2018, assigned to the assignee hereof, and expressly incorporated hereinby reference in its entirety.

TECHNICAL FIELD

Various aspects described herein generally relate to wirelesscommunication systems, and more particularly, to simplified celllocation information sharing for positioning purposes.

BACKGROUND

Wireless communication systems have developed through variousgenerations, including a first-generation analog wireless phone service(1G), a second-generation (2G) digital wireless phone service (includinginterim 2.5G and 2.75G networks), a third-generation (3G) high speeddata, Internet-capable wireless service and a fourth-generation (4G)service (e.g., Long Term Evolution (LTE) or WiMax). There are presentlymany different types of wireless communication systems in use, includingCellular and Personal Communications Service (PCS) systems. Examples ofknown cellular systems include the cellular Analog Advanced Mobile PhoneSystem (AMPS), and digital cellular systems based on Code DivisionMultiple Access (CDMA), Frequency Division Multiple Access (FDMA), TimeDivision Multiple Access (TDMA), the Global System for Mobile access(GSM) variation of TDMA, etc.

A fifth generation (5G) mobile standard calls for higher data transferspeeds, greater numbers of connections, and better coverage, among otherimprovements. The 5G standard, according to the Next Generation MobileNetworks Alliance, is designed to provide data rates of several tens ofmegabits per second to each of tens of thousands of users, with 1gigabit per second to tens of workers on an office floor. Severalhundreds of thousands of simultaneous connections should be supported inorder to support large sensor deployments. Consequently, the spectralefficiency of 5G mobile communications should be significantly enhancedcompared to the current 4G standard. Furthermore, signaling efficienciesshould be enhanced and latency should be substantially reduced comparedto current standards.

Some wireless communication networks, such as 5G, support operation atvery high and even extremely-high frequency (EHF) bands, such asmillimeter wave (mmW) frequency bands (generally, wavelengths of 1 mm to10 mm, or 30 to 300 GHz). These extremely high frequencies may supportvery high throughput such as up to six gigabits per second (Gbps). Oneof the challenges for wireless communication at very high or extremelyhigh frequencies, however, is that a significant propagation loss mayoccur due to the high frequency. As the frequency increases, thewavelength may decrease, and the propagation loss may increase as well.At mmW frequency bands, the propagation loss may be severe. For example,the propagation loss may be on the order of 22 to 27 dB, relative tothat observed in either the 2.4 GHz, or 5 GHz bands.

Propagation loss is also an issue in Multiple Input-Multiple Output(MIMO) and massive MIMO systems in any band. The term MIMO as usedherein will generally refer to both MIMO and massive MIMO. MIMO is amethod for multiplying the capacity of a radio link by using multipletransmit and receive antennas to exploit multipath propagation.Multipath propagation occurs because radio frequency (RF) signals notonly travel by the shortest path between the transmitter and receiver,which may be a line of sight (LOS) path, but also over a number of otherpaths as they spread out from the transmitter and reflect off otherobjects such as hills, buildings, water, and the like on their way tothe receiver. A transmitter in a MIMO system includes multiple antennasand takes advantage of multipath propagation by directing these antennasto each transmit the same RF signals on the same radio channel to areceiver. The receiver is also equipped with multiple antennas tuned tothe radio channel that can detect the RF signals sent by thetransmitter. As the RF signals arrive at the receiver (some RF signalsmay be delayed due to the multipath propagation), the receiver cancombine them into a single RF signal. Because the transmitter sends eachRF signal at a lower power level than it would send a single RF signal,propagation loss is also an issue in a MIMO system.

To address propagation loss issues in mmW band systems and MIMO systems,transmitters may use beamforming to extend RF signal coverage. Inparticular, transmit beamforming is a technique for emitting an RFsignal in a specific direction, whereas receive beamforming is atechnique used to increase receive sensitivity of RF signals that arriveat a receiver along a specific direction. Transmit beamforming andreceive beamforming may be used in conjunction with each other orseparately, and references to “beamforming” may hereinafter refer totransmit beamforming, receive beamforming, or both. Traditionally, whena transmitter broadcasts an RF signal, it broadcasts the RF signal innearly all directions determined by the fixed antenna pattern orradiation pattern of the antenna. With beamforming, the transmitterdetermines where a given receiver is located relative to the transmitterand projects a stronger downlink RF signal in that specific direction,thereby providing a faster (in terms of data rate) and stronger RFsignal for the receiver. To change the directionality of the RF signalwhen transmitting, a transmitter can control the phase and relativeamplitude of the RF signal broadcasted by each antenna. For example, atransmitter may use an array of antennas (also referred to as a “phasedarray” or an “antenna array”) that creates a beam of RF waves that canbe “steered” to point in different directions, without actually movingthe antennas. Specifically, the RF current is fed to the individualantennas with the correct phase relationship so that the radio wavesfrom the separate antennas add together to increase the radiation in adesired direction, while cancelling the radio waves from the separateantennas to suppress radiation in undesired directions.

To support position estimations in terrestrial wireless networks, amobile device can be configured to measure and report the observed timedifference of arrival (OTDOA) or reference signal timing difference(RSTD) between reference RF signals received from two or more networknodes (e.g., different base stations or different transmission points(e.g., antennas) belonging to the same base station).

Where a transmitter uses beamforming to transmit RF signals, the beamsof interest for data communication between the transmitter and receiverwill be the beams carrying RF signals having the highest received signalstrength (or highest received Signal to Noise plus Interference Ratio(SINR), for example, in the presence of a directional interferingsignal). However, the receiver's ability to perform certain tasks maysuffer when the receiver relies upon the beam with the highest receivedsignal strength. For example, in a scenario where the beam with thehighest received signal strength travels over a non-LOS (NLOS) path thatis longer than the shortest path (i.e., a LOS path or a shortest NLOSpath), the RF signals may arrive later than RF signal(s) received overthe shortest path due to propagation delay. Accordingly, if the receiveris performing a task that requires precise timing measurements and thebeam with the highest received signal strength is affected by longerpropagation delay, then the beam with the highest received signalstrength may not be optimal for the task at hand.

SUMMARY

The following presents a simplified summary relating to one or moreaspects disclosed herein. As such, the following summary should not beconsidered an extensive overview relating to all contemplated aspects,nor should the following summary be regarded to identify key or criticalelements relating to all contemplated aspects or to delineate the scopeassociated with any particular aspect. Accordingly, the followingsummary has the sole purpose to present certain concepts relating to oneor more aspects relating to the mechanisms disclosed herein in asimplified form to precede the detailed description presented below.

An aspect is directed to a method of a user equipment (UE). The methodcomprises receiving a plurality of positioning reference signals (PRS)from a plurality of cells. The plurality of cells is grouped into one ormore cell groups. Each cell group comprises one or more member cells inwhich each member cell is one of the plurality of cells. Each cell groupis associated with an attribute set comprising one or more attributes.For each cell group, all member cells have all attributes of theassociated attribute set in common. The plurality of PRSs includes aplurality of PRS IDs. For each cell group, the PRS ID of each membercell indicates a membership of that member cell in that cell group. Themethod also comprises detecting a plurality of time of arrivals (TOA) ofthe plurality of PRSs. The method further comprises deriving a timedifference of arrival (TDOA) vector from the plurality of TOAs, andsending the TDOA vector to a network entity. The TDOA vector includesmultiple TOA related measurements of multiple cells.

An aspect is directed to a method of a network entity. The methodcomprises configuring a plurality of cells to transmit a plurality ofpositioning reference signals (PRS) to a user equipment (UE). Theplurality of cells is grouped into one or more cell groups. Each cellgroup comprises one or more member cells in which each member cell isone of the plurality of cells. Each cell group is associated with anattribute set comprising one or more attributes. For each cell group,all member cells have all attributes of the associated attribute set incommon. The plurality of PRSs includes a plurality of PRS IDs. For eachcell group, a PRS ID of each member cell indicates a membership of thatmember cell in that cell group. The method also comprises receiving atime difference of arrival (TDOA) vector from the UE. The method furthercomprises determining a position of the UE based on the TDOA vector. TheTDOA vector includes multiple TOA related measurements of multiplecells.

An aspect is directed to a user equipment (UE) comprising a memory, atransceiver, and a processor coupled to the memory and the transceiver.The processor, the memory, and the transceiver are configured to receivea plurality of positioning reference signals (PRS) from a plurality ofcells. The plurality of cells is grouped into one or more cell groups.Each cell group comprises one or more member cells in which each membercell is one of the plurality of cells. Each cell group is associatedwith an attribute set comprising one or more attributes. For each cellgroup, all member cells have all attributes of the associated attributeset in common. The plurality of PRSs includes a plurality of PRS IDs.For each cell group, a PRS ID of each member cell indicates a membershipof that member cell in that cell group. The processor, the memory, andthe transceiver are also configured to detect a plurality of time ofarrivals (TOA) of the plurality of PRSs. The processor, the memory, andthe transceiver are further configured to derive a time difference ofarrival (TDOA) vector from the plurality of TOAs. The processor, thememory, and the transceiver are yet further configured to send the TDOAvector to a network entity. The TDOA vector includes multiple TOArelated measurements of multiple cells.

An aspect is directed to a network entity comprising a memory, atransceiver, and a processor coupled to the memory and the transceiver.The processor, the memory, and the transceiver are configured toconfigure a plurality of cells to transmit a plurality of positioningreference signals (PRS) to a user equipment (UE). The plurality of cellsis grouped into one or more cell groups. Each cell group comprises oneor more member cells in which each member cell is one of the pluralityof cells. Each cell group is associated with an attribute set comprisingone or more attributes. For each cell group, all member cells have allattributes of the associated attribute set in common. The plurality ofPRSs includes a plurality of PRS IDs. For each cell group, a PRS ID ofeach member cell indicates a membership of that member cell in that cellgroup. The processor, the memory, and the transceiver are alsoconfigured to receive a time difference of arrival (TDOA) vector fromthe UE. The processor, the memory, and the transceiver are furtherconfigured to determine a position of the UE based on the TDOA vector.The TDOA vector includes multiple TOA related measurements of multiplecells.

An aspect is directed to a user equipment (UE). The UE comprises meansfor receiving a plurality of positioning reference signals (PRS) from aplurality of cells. The plurality of cells is grouped into one or morecell groups. Each cell group comprises one or more member cells in whicheach member cell is one of the plurality of cells. Each cell group isassociated with an attribute set comprising one or more attributes. Foreach cell group, all member cells have all attributes of the associatedattribute set in common. The plurality of PRSs includes a plurality ofPRS IDs. For each cell group, a PRS ID of each member cell indicates amembership of that member cell in that cell group. The UE also comprisesmeans for detecting a plurality of time of arrivals (TOA) of theplurality of PRSs. The UE further comprises means for deriving a timedifference of arrival (TDOA) vector from the plurality of TOAs, andmeans for sending the TDOA vector to a network entity. The TDOA vectorincludes multiple TOA related measurements of multiple cells.

An aspect is directed to a network entity. The network entity comprisesmeans for configuring a plurality of cells to transmit a plurality ofpositioning reference signals (PRS) to a user equipment (UE). Theplurality of cells is grouped into one or more cell groups. Each cellgroup comprises one or more member cells in which each member cell isone of the plurality of cells. Each cell group is associated with anattribute set comprising one or more attributes. For each cell group,all member cells have all attributes of the associated attribute set incommon. The plurality of PRSs includes a plurality of PRS IDs. For eachcell group, a PRS ID of each member cell indicates a membership of thatmember cell in that cell group. The network entity also comprises meansfor receiving a time difference of arrival (TDOA) vector from the UE.The network entity further comprises means for determining a position ofthe UE based on the TDOA vector. The TDOA vector includes multiple TOArelated measurements of multiple cells.

An aspect is directed to a non-transitory computer-readable mediumcontaining instructions executable by a user equipment (UE) being storedthereon. The instructions cause the UE to receive a plurality ofpositioning reference signals (PRS) from a plurality of cells. Theplurality of cells is grouped into one or more cell groups. Each cellgroup comprises one or more member cells in which each member cell isone of the plurality of cells. Each cell group is associated with anattribute set comprising one or more attributes. For each cell group,all member cells have all attributes of the associated attribute set incommon. The plurality of PRSs includes a plurality of PRS IDs. For eachcell group, a PRS ID of each member cell indicates a membership of thatmember cell in that cell group. The instructions also cause the UE todetect a plurality of time of arrivals (TOA) of the plurality of PRSs.The instructions further cause the UE to derive a time difference ofarrival (TDOA) vector from the plurality of TOAs, and send the TDOAvector to a network entity. The TDOA vector includes multiple TOArelated measurements of multiple cells.

An aspect is directed to a non-transitory computer-readable mediumcontaining instructions executable by a network entity being storedthereon. The instructions cause the network entity to configure aplurality of cells to transmit a plurality of positioning referencesignals (PRS) to a user equipment (UE). The plurality of cells isgrouped into one or more cell groups. Each cell group comprises one ormore member cells in which each member cell is one of the plurality ofcells. Each cell group is associated with an attribute set comprisingone or more attributes. For each cell group, all member cells have allattributes of the associated attribute set in common. The plurality ofPRSs includes a plurality of PRS IDs. For each cell group, a PRS ID ofeach member cell indicates a membership of that member cell in that cellgroup. The instructions also cause the network entity to receive a timedifference of arrival (TDOA) vector from the UE. The instructionsfurther cause the network entity to determine a position of the UE basedon the TDOA vector. The TDOA vector includes multiple TOA relatedmeasurements of multiple cells.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the various aspects described herein andmany attendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingswhich are presented solely for illustration and not limitation, and inwhich:

FIG. 1 illustrates an exemplary wireless communications system accordingto various aspects;

FIGS. 2A and 2B illustrate example wireless network structures accordingto various aspects;

FIG. 3A illustrates an exemplary base station and an exemplary UE in anaccess network according to various aspects;

FIG. 3B illustrates an exemplary server according to various aspects;

FIG. 4 illustrates an exemplary wireless communications system accordingto various aspects;

FIG. 5 illustrates an exemplary wireless communications system accordingto various aspects;

FIG. 6A is a graph showing the RF channel response at a UE over timeaccording to various aspects;

FIG. 6B illustrates an exemplary separation of clusters in angle ofdeparture (AoD) according to various aspects;

FIG. 7 illustrates an example scenario for observed time difference ofarrival (OTDOA) based position estimating technique according to variousaspects;

FIG. 8 an example scenario for utilizing beam sweeping for positioningestimation according to various aspects;

FIG. 9 illustrates an example flow for position estimation according tovarious aspects;

FIG. 10 illustrates an example flow for selecting TOAs to improvepositioning accuracy according to various aspects;

FIG. 11 illustrates a scenario for pruning the TOAs according to variousaspects; and

FIG. 12 illustrates a flow chart of an exemplary method of a UE-assistedpositioning determination according to various aspects.

DETAILED DESCRIPTION

Various aspects described herein generally relate to wirelesscommunication systems, and more particularly, to phase difference ofarrival (PDoA) and angle of departure (AoD) estimation. In an aspect, anetwork entity may provide a base station almanac (BSA) to a UE. The BSAmay indicate a set of transmission points associated with a basestation, and the UE may perform measurements on the signal transmittedfrom the set of transmission points. In particular, the UE may determinethe PDoAs of the signals. The UE may further determine or estimate AoDsof the signals based on the PDoAs and/or may provide the PDoAs to thenetwork entity.

These and other aspects are disclosed in the following description andrelated drawings to show specific examples relating to exemplaryaspects. Alternate aspects will be apparent to those skilled in thepertinent art upon reading this disclosure, and may be constructed andpracticed without departing from the scope or spirit of the disclosure.Additionally, well-known elements will not be described in detail or maybe omitted so as to not obscure the relevant details of the aspectsdisclosed herein.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects. Likewise, the term “aspects” does not require that allaspects include the discussed feature, advantage, or mode of operation.

The terminology used herein describes particular aspects only and shouldnot be construed to limit any aspects disclosed herein. As used herein,the singular forms “a,” “an,” and “the” are intended to include theplural forms as well, unless the context clearly indicates otherwise.Those skilled in the art will further understand that the terms“comprises,” “comprising,” “includes,” and/or “including,” as usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Further, various aspects may be described in terms of sequences ofactions to be performed by, for example, elements of a computing device.Those skilled in the art will recognize that various actions describedherein can be performed by specific circuits (e.g., an applicationspecific integrated circuit (ASIC)), by program instructions beingexecuted by one or more processors, or by a combination of both.Additionally, these sequences of actions described herein can beconsidered to be embodied entirely within any form of non-transitorycomputer-readable medium having stored thereon a corresponding set ofcomputer instructions that upon execution would cause an associatedprocessor to perform the functionality described herein. Thus, thevarious aspects described herein may be embodied in a number ofdifferent forms, all of which have been contemplated to be within thescope of the claimed subject matter. In addition, for each of theaspects described herein, the corresponding form of any such aspects maybe described herein as, for example, “logic configured to” and/or otherstructural components configured to perform the described action.

As used herein, the terms “user equipment” (or “UE”), “user device,”“user terminal,” “client device,” “communication device,” “wirelessdevice,” “wireless communications device,” “handheld device,” “mobiledevice,” “mobile terminal,” “mobile station,” “handset,” “accessterminal,” “subscriber device,” “subscriber terminal,” “subscriberstation,” “terminal,” and variants thereof may interchangeably refer toany suitable mobile or stationary device that can receive wirelesscommunication and/or navigation signals. These terms are also intendedto include devices which communicate with another device that canreceive wireless communication and/or navigation signals such as byshort-range wireless, infrared, wireline connection, or otherconnection, regardless of whether satellite signal reception, assistancedata reception, and/or position-related processing occurs at the deviceor at the other device. In addition, these terms are intended to includeall devices, including wireless and wireline communication devices, thatcan communicate with a core network via a radio access network (RAN),and through the core network the UEs can be connected with externalnetworks such as the Internet and with other UEs. Of course, othermechanisms of connecting to the core network and/or the Internet arealso possible for the UEs, such as over a wired access network, awireless local area network (WLAN) (e.g., based on IEEE 802.11, etc.)and so on. UEs can be embodied by any of a number of types of devicesincluding but not limited to printed circuit (PC) cards, compact flashdevices, external or internal modems, wireless or wireline phones,smartphones, tablets, tracking devices, asset tags, and so on. Acommunication link through which UEs can send signals to a RAN is calledan uplink channel (e.g., a reverse traffic channel, a reverse controlchannel, an access channel, etc.). A communication link through whichthe RAN can send signals to UEs is called a downlink or forward linkchannel (e.g., a paging channel, a control channel, a broadcast channel,a forward traffic channel, etc.). As used herein the term trafficchannel (TCH) can refer to either an uplink/reverse or downlink/forwardtraffic channel.

According to various aspects, FIG. 1 illustrates an exemplary wirelesscommunications system 100. The wireless communications system 100 (whichmay also be referred to as a wireless wide area network (WWAN)) mayinclude various base stations 102 and various UEs 104. The base stations102 may include macro cells (high power cellular base stations) and/orsmall cells (low power cellular base stations), wherein the macro cellsmay include Evolved NodeBs (eNBs), where the wireless communicationssystem 100 corresponds to an LTE network, or gNodeBs (gNBs), where thewireless communications system 100 corresponds to a 5G network or acombination of both, and the small cells may include femtocells,picocells, microcells, etc.

The base stations 102 may collectively form a Radio Access Network (RAN)and interface with an Evolved Packet Core (EPC) or Next Generation Core(NGC) through backhaul links. In addition to other functions, the basestations 102 may perform functions that relate to one or more oftransferring user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, RAN sharing, multimedia broadcast multicast service(MBMS), subscriber and equipment trace, RAN information management(RIM), paging, positioning, and delivery of warning messages. The basestations 102 may communicate with each other directly or indirectly(e.g., through the EPC/NGC) over backhaul links 134, which may be wiredor wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. In an aspect, although notshown in FIG. 1, coverage areas 110 may be subdivided into a pluralityof cells (e.g., three), or sectors, each cell corresponding to a singleantenna or array of antennas of a base station 102. As used herein, theterm “cell” or “sector” may correspond to one of a plurality of cells ofa base station 102, or to the base station 102 itself, depending on thecontext.

While neighboring macro cell geographic coverage areas 110 may partiallyoverlap (e.g., in a handover region), some of the geographic coverageareas 110 may be substantially overlapped by a larger geographiccoverage area 110. For example, a small cell base station 102′ may havea coverage area 110′ that substantially overlaps with the coverage area110 of one or more macro cell base stations 102. A network that includesboth small cell and macro cells may be known as a heterogeneous network.A heterogeneous network may also include Home eNBs (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use MIMO antennatechnology, including spatial multiplexing, beamforming, and/or transmitdiversity. The communication links may be through one or more carriers.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or less carriers may be allocated for DL than for UL).

The wireless communications system 100 may further include a wirelesslocal area network (WLAN) access point (AP) 150 in communication withWLAN stations (STAs) 152 via communication links 154 in an unlicensedfrequency spectrum (e.g., 5 GHz). When communicating in an unlicensedfrequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150 may performa clear channel assessment (CCA) prior to communicating in order todetermine whether the channel is available.

The small cell base station 102′ may operate in a licensed and/or anunlicensed frequency spectrum. When operating in an unlicensed frequencyspectrum, the small cell base station 102′ may employ LTE or 5Gtechnology and use the same 5 GHz unlicensed frequency spectrum as usedby the WLAN AP 150. The small cell base station 102′, employing LTE/5Gin an unlicensed frequency spectrum, may boost coverage to and/orincrease capacity of the access network. LTE in an unlicensed spectrummay be referred to as LTE-unlicensed (LTE-U), licensed assisted access(LAA), or MulteFire.

The wireless communications system 100 may further include a mmW basestation 180 that may operate in mmW frequencies and/or near mmWfrequencies in communication with a UE 182. Extremely high frequency(EHF) is part of the RF in the electromagnetic spectrum. EHF has a rangeof 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10millimeters. Radio waves in this band may be referred to as a millimeterwave. Near mmW may extend down to a frequency of 3 GHz with a wavelengthof 100 millimeters. The super high frequency (SHF) band extends between3 GHz and 30 GHz, also referred to as centimeter wave. Communicationsusing the mmW/near mmW radio frequency band have high path loss and arelatively short range. The mmW base station 180 may utilize beamforming184 with the UE 182 to compensate for the extremely high path loss andshort range. Further, it will be appreciated that in alternativeconfigurations, one or more base stations 102 may also transmit usingmmW or near mmW and beamforming. Accordingly, it will be appreciatedthat the foregoing illustrations are merely examples and should not beconstrued to limit the various aspects disclosed herein.

The wireless communications system 100 may further include one or moreUEs, such as UE 190, that connects indirectly to one or morecommunication networks via one or more device-to-device (D2D)peer-to-peer (P2P) links. In the embodiment of FIG. 1, UE 190 has a D2DP2P link 192 with one of the UEs 104 connected to one of the basestations 102 (e.g., through which UE 190 may indirectly obtain cellularconnectivity) and a D2D P2P link 194 with WLAN STA 152 connected to theWLAN AP 150 (through which UE 190 may indirectly obtain WLAN-basedInternet connectivity). In an example, the D2D P2P links 192-194 may besupported with any well-known D2D radio access technology (RAT), such asLTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth, and so on.

According to various aspects, FIG. 2A illustrates an example wirelessnetwork structure 200. For example, a Next Generation Core (NGC) 210 canbe viewed functionally as control plane functions 214 (e.g., UEregistration, authentication, network access, gateway selection, etc.)and user plane functions 212, (e.g., UE gateway function, access to datanetworks, IP routing, etc.) which operate cooperatively to form the corenetwork. User plane interface (NG-U) 213 and control plane interface(NG-C) 215 connect the gNB 222 to the NGC 210 and specifically to thecontrol plane functions 214 and user plane functions 212. In anadditional configuration, an eNB 224 may also be connected to the NGC210 via NG-C 215 to the control plane functions 214 and NG-U 213 to userplane functions 212. Further, eNB 224 may directly communicate with gNB222 via a backhaul connection 223. Accordingly, in some configurations,the New RAN 220 may only have one or more gNBs 222, while otherconfigurations include one or more of both eNBs 224 and gNBs 222. EithergNB 222 or eNB 224 may communicate with UEs 240 (e.g., any of the UEsdepicted in FIG. 1, such as UEs 104, UE 182, UE 190, etc.). Anotheroptional aspect may include Location Server 230 which may be incommunication with the NGC 210 to provide location assistance for UEs240. The location server 230 can be implemented as a plurality ofstructurally separate servers, or alternately may each correspond to asingle server. The location server 230 can be configured to support oneor more location services for UEs 240 that can connect to the locationserver 230 via the core network, NGC 210, and/or via the Internet (notillustrated). Further, the location server 230 may be integrated into acomponent of the core network, or alternatively may be external to thecore network.

According to various aspects, FIG. 2B illustrates another examplewireless network structure 250. For example, Evolved Packet Core (EPC)260 can be viewed functionally as control plane functions, MobilityManagement Entity (MME) 264 and user plane functions, Packet DataNetwork Gateway/Serving Gateway (P/SGW) 262, which operate cooperativelyto form the core network. S1 user plane interface (S1-U) 263 and S1control plane interface (S1-MME) 265 connect the eNB 224 to the EPC 260and specifically to MME 264 and P/SGW 262. In an additionalconfiguration, a gNB 222 may also be connected to the EPC 260 via S1-MME265 to MME 264 and S1-U 263 to P/SGW 262. Further, eNB 224 may directlycommunicate to gNB 222 via the backhaul connection 223, with or withoutgNB direct connectivity to the EPC 260. Accordingly, in someconfigurations, the New RAN 220 may only have one or more gNBs 222,while other configurations include one or more of both eNBs 224 and gNBs222. Either gNB 222 or eNB 224 may communicate with UEs 240 (e.g., anyof the UEs depicted in FIG. 1, such as UEs 104, UE 182, UE 190, etc.).Another optional aspect may include Location Server 230 which may be incommunication with the EPC 260 to provide location assistance for UEs240. The location server 230 can be implemented as a plurality ofstructurally separate servers, or alternately may each correspond to asingle server. The location server 230 can be configured to support oneor more location services for UEs 240 that can connect to the locationserver 230 via the core network, EPC 260, and/or via the Internet (notillustrated).

According to various aspects, FIG. 3A illustrates an exemplary basestation 310 (e.g., an eNB, a gNB, a small cell AP, a WLAN AP, etc.) incommunication with an exemplary UE 350 in a wireless network. In the DL,IP packets from the core network (NGC 210/EPC 260) may be provided to acontroller/processor 375. The controller/processor 375 implementsfunctionality for a radio resource control (RRC) layer, a packet dataconvergence protocol (PDCP) layer, a radio link control (RLC) layer, anda medium access control (MAC) layer. The controller/processor 375provides RRC layer functionality associated with broadcasting of systeminformation (e.g., MIB, SIBs), RRC connection control (e.g., RRCconnection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter-RAT mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, scheduling informationreporting, error correction, priority handling, and logical channelprioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement Layer-1 functionality associated with various signalprocessing functions. Layer-1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to one or moredifferent antennas 320 via a separate transmitter 318TX. Eachtransmitter 318TX may modulate an RF carrier with a respective spatialstream for transmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the RXprocessor 356. The TX processor 368 and the RX processor 356 implementLayer-1 functionality associated with various signal processingfunctions. The RX processor 356 may perform spatial processing on theinformation to recover any spatial streams destined for the UE 350. Ifmultiple spatial streams are destined for the UE 350, they may becombined by the RX processor 356 into a single OFDM symbol stream. TheRX processor 356 then converts the OFDM symbol stream from thetime-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and de-interleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements Layer-3 and Layer-2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the core network. Thecontroller/processor 359 is also responsible for error detection.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by the channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the core network. Thecontroller/processor 375 is also responsible for error detection.

FIG. 3B illustrates an exemplary server 300B. In an example, the server300B may correspond to an example configuration of the location server230 described above. The server 300B includes a processor 301B coupledto volatile memory 302B and a large capacity nonvolatile memory, such asa disk drive 303B. The server 300B may also include a floppy disc drive,compact disc (CD) or DVD disc drive 306B coupled to the processor 301B.The server 300B may also include network access ports 304B coupled tothe processor 301B for establishing data connections with a network307B, such as a local area network coupled to other broadcast systemcomputers and servers or to the Internet.

FIG. 4 illustrates an exemplary wireless communications system 400according to various aspects of the disclosure. In the example of FIG.4, a UE 404, which may correspond to any of the UEs described above withrespect to FIG. 1 (e.g., UEs 104, UE 182, UE 190, etc.), is attemptingto calculate an estimate of its position, or assist another entity(e.g., a base station or core network component, another UE, a locationserver, a third party application, etc.) to calculate an estimate of itsposition. The UE 404 may communicate wirelessly with a plurality of basestations 402 a-d (collectively, base stations 402), which may correspondto any combination of base stations 102 or 180 and/or WLAN AP 150 inFIG. 1, using RF signals and standardized protocols for the modulationof the RF signals and the exchange of information packets. By extractingdifferent types of information from the exchanged RF signals, andutilizing the layout of the wireless communications system 400 (i.e.,the base stations locations, geometry, etc.), the UE 404 may determineits position, or assist in the determination of its position, in apredefined reference coordinate system. In an aspect, the UE 404 mayspecify its position using a two-dimensional coordinate system; however,the aspects disclosed herein are not so limited, and may also beapplicable to determining positions using a three-dimensional coordinatesystem, if the extra dimension is desired. Additionally, while FIG. 4illustrates one UE 404 and four base stations 402, as will beappreciated, there may be more UEs 404 and more or fewer base stations402.

To support position estimates, the base stations 402 may be configuredto broadcast reference RF signals (e.g., Positioning Reference Signals(PRS), Cell-specific Reference Signals (CRS), Channel State InformationReference Signals (CSI-RS), synchronization signals, etc.) to UEs 404 intheir coverage area to enable a UE 404 to measure reference RF signaltiming differences (e.g., OTDOA or RSTD) between pairs of network nodesand/or to identify the beam that best excite the LOS or shortest radiopath between the UE 404 and the transmitting base stations 402.Identifying the LOS/shortest path beam(s) is of interest not onlybecause these beams can subsequently be used for OTDOA measurementsbetween a pair of base stations 402, but also because identifying thesebeams can directly provide some positioning information based on thebeam direction. Moreover, these beams can subsequently be used for otherposition estimation methods that require precise ToA, such as round-triptime estimation based methods.

As used herein, a “network node” may be a base station 402, a cell of abase station 402, a remote radio head, an antenna of a base station 402,where the locations of the antennas of a base station 402 are distinctfrom the location of the base station 402 itself, or any other networkentity capable of transmitting reference signals. Further, as usedherein, a “node” may refer to either a network node or a UE.

A location server (e.g., location server 230) may send assistance datato the UE 404 that includes an identification of one or more neighborcells of base stations 402 and configuration information for referenceRF signals transmitted by each neighbor cell. Alternatively, theassistance data can originate directly from the base stations 402themselves (e.g., in periodically broadcasted overhead messages, etc.).Alternatively, the UE 404 can detect neighbor cells of base stations 402itself without the use of assistance data. The UE 404 (e.g., based inpart on the assistance data, if provided) can measure and (optionally)report the OTDOA from individual network nodes and/or RSTDs betweenreference RF signals received from pairs of network nodes. Using thesemeasurements and the known locations of the measured network nodes(i.e., the base station(s) 402 or antenna(s) that transmitted thereference RF signals that the UE 404 measured), the UE 404 or thelocation server can determine the distance between the UE 404 and themeasured network nodes and thereby calculate the location of the UE 404.

The term “position estimate” is used herein to refer to an estimate of aposition for a UE 404, which may be geographic (e.g., may comprise alatitude, longitude, and possibly altitude) or civic (e.g., may comprisea street address, building designation, or precise point or area withinor nearby to a building or street address, such as a particular entranceto a building, a particular room or suite in a building, or a landmarksuch as a town square). A position estimate may also be referred to as a“location,” a “position,” a “fix,” a “position fix,” a “location fix,” a“location estimate,” a “fix estimate,” or by some other term. The meansof obtaining a location estimate may be referred to generically as“positioning,” “locating,” or “position fixing.” A particular solutionfor obtaining a position estimate may be referred to as a “positionsolution.” A particular method for obtaining a position estimate as partof a position solution may be referred to as a “position method” or as a“positioning method.”

The term “base station” may refer to a single physical transmissionpoint or to multiple physical transmission points that may or may not beco-located. For example, where the term “base station” refers to asingle physical transmission point, the physical transmission point maybe an antenna of the base station (e.g., base station 402) correspondingto a cell of the base station. Where the term “base station” refers tomultiple co-located physical transmission points, the physicaltransmission points may be an array of antennas (e.g., as in a MIMOsystem or where the base station employs beamforming) of the basestation. Where the term “base station” refers to multiple non-co-locatedphysical transmission points, the physical transmission points may be aDistributed Antenna System (DAS) (a network of spatially separatedantennas connected to a common source via a transport medium) or aRemote Radio Head (RRH) (a remote base station connected to a servingbase station). Alternatively, the non-co-located physical transmissionpoints may be the serving base station receiving the measurement reportfrom the UE (e.g., UE 404) and a neighbor base station whose referenceRF signals the UE is measuring. Thus, FIG. 4 illustrates an aspect inwhich base stations 402 a and 402 b form a DAS/RRH 420. For example, thebase station 402 a may be the serving base station of the UE 404 and thebase station 402 b may be a neighbor base station of the UE 404. Assuch, the base station 402 b may be the RRH of the base station 402 a.The base stations 402 a and 402 b may communicate with each other over awired or wireless link 422.

To accurately determine the position of the UE 404 using the OTDOAsand/or RSTDs between RF signals received from pairs of network nodes,the UE 404 needs to measure the reference RF signals received over theLOS path (or the shortest NLOS path where an LOS path is not available),between the UE 404 and a network node (e.g., base station 402, antenna).However, RF signals travel not only by the LOS/shortest path between thetransmitter and receiver, but also over a number of other paths as theRF signals spread out from the transmitter and reflect off other objectssuch as hills, buildings, water, and the like on their way to thereceiver. Thus, FIG. 4 illustrates a number of LOS paths 410 and anumber of NLOS paths 412 between the base stations 402 and the UE 404.Specifically, FIG. 4 illustrates base station 402 a transmitting over anLOS path 410 a and an NLOS path 412 a, base station 402 b transmittingover an LOS path 410 b and two NLOS paths 412 b, base station 402 ctransmitting over an LOS path 410 c and an NLOS path 412 c, and basestation 402 d transmitting over two NLOS paths 412 d. As illustrated inFIG. 4, each NLOS path 412 reflects off some object 430 (e.g., abuilding). As will be appreciated, each LOS path 410 and NLOS path 412transmitted by a base station 402 may be transmitted by differentantennas of the base station 402 (e.g., as in a MIMO system), or may betransmitted by the same antenna of a base station 402 (therebyillustrating the propagation of an RF signal). Further, as used herein,the term “LOS path” refers to the shortest path between a transmitterand receiver, and may not be an actual LOS path, but rather, theshortest NLOS path.

Each LOS path 410 and NLOS path 412 represents the path followed by anRF signal. An “RF signal” comprises an electromagnetic wave thattransports information through the space between the transmitter and thereceiver. As illustrated in FIG. 4 and as described further below, thereceiver (e.g., UE 404) may receive multiple “RF signals” correspondingto each transmitted RF signal due to the propagation characteristics ofRF signals through multipath channels. More specifically, when atransmitter (e.g., a base station 402) transmits an RF signal, the RFsignal received at the receiver (e.g., UE 404) is the sum oraccumulation of the RF signals received over multiple paths. Forexample, the UE 404 may combine the RF signals received over the LOSpath 410 c and the NLOS path 412 c into a single RF signal. Since signalpaths may have different lengths and arrive at the receiver fromdifferent directions, as illustrated in FIG. 4, the RF signal from eachpath is accordingly delayed and arrives at a certain angle. Thisdirectional effect is more pronounced at higher frequencies, such asmmW.

In receive beamforming, the receiver uses a receive beam to amplify RFsignals detected on a given channel. For example, the receiver canincrease the gain setting and/or adjust the phase setting of an array ofantennas (e.g., antennas 352 in FIG. 3) in a particular direction toamplify (e.g., to increase the gain level of) the RF signals receivedfrom that direction. Thus, when a receiver is said to beamform in acertain direction, it means the beam gain in that direction is highrelative to the beam gain along other directions, or the beam gain inthat direction is the highest compared to the beam gain in thatdirection of all other receive beams available to the receiver. Thisresults in a stronger received signal strength (e.g., RSRP, SINR, etc.)of the RF signals received from that direction.

FIG. 5 illustrates an exemplary wireless communications system 500according to various aspects of the disclosure. In the example of FIG.5, a UE 504, which may correspond to UE 404 in FIG. 4, is attempting tocalculate an estimate of its position, or to assist another entity(e.g., a base station or core network component, another UE, a locationserver, a third party application, etc.) to calculate an estimate of itsposition. The UE 504 may communicate wirelessly with a base station 502,which may correspond to one of base stations 402 in FIG. 4, using RFsignals and standardized protocols for the modulation of the RF signalsand the exchange of information packets.

As illustrated in FIG. 5, the base station 502 is utilizing beamformingto transmit a plurality of beams 511-515 of RF signals. Each beam511-515 may be formed and transmitted by an array of antennas of thebase station 502. Although FIG. 5 illustrates a base station 502transmitting five beams, as will be appreciated, there may be more orfewer than five beams, beam shapes such as peak gain, width, andside-lobe gains may differ amongst the transmitted beams, and some ofthe beams may be transmitted by a different base station.

A beam index may be assigned to each of the plurality of beams 511-515for purposes of distinguishing RF signals associated with one beam fromRF signals associated with another beam. Moreover, the RF signalsassociated with a particular beam of the plurality of beams 511-515 maycarry a beam index indicator. A beam index may also be derived from thetime of transmission, e.g., frame, slot and/or OFDM symbol number, ofthe RF signal. The beam index indicator may be, for example, a three-bitfield for uniquely distinguishing up to eight beams. If two different RFsignals having different beam indices are received, this would indicatethat the RF signals were transmitted using different beams. If twodifferent RF signals share a common beam index, this would indicate thatthe different RF signals are transmitted using the same beam. Anotherway to describe that two RF signals are transmitted using the same beamis to say that the antenna port(s) used for the transmission of thefirst RF signal are spatially quasi-collocated with the antenna port(s)used for the transmission of the second RF signal.

In the example of FIG. 5, the UE 504 receives an NLOS stream 523 of RFsignals transmitted on beam 513 and an LOS stream 524 of RF signalstransmitted on beam 514. Although FIG. 5 illustrates the NLOS stream 523and the LOS stream 524 as single lines (dashed and solid, respectively),as will be appreciated, the NLOS stream 523 and the LOS stream 524 mayeach comprise multiple rays (i.e., a “cluster”) by the time they reachthe UE 504 due, for example, to the propagation characteristics of RFsignals through multipath channels. For example, a cluster of RF signalsis formed when an electromagnetic wave is reflected off of multiplesurfaces of an object, and reflections arrive at the receiver (e.g., UE504) from roughly the same angle, each travelling a few wavelengths(e.g., centimeters) more or less than others. A “cluster” of received RFsignals generally corresponds to a single transmitted RF signal.

In the example of FIG. 5, the NLOS stream 523 is not originally directedat the UE 504, although, as will be appreciated, it could be, as are theRF signals on the NLOS paths 412 in FIG. 4. However, it is reflected offa reflector 540 (e.g., a building) and reaches the UE 504 withoutobstruction, and therefore, may still be a relatively strong RF signal.In contrast, the LOS stream 524 is directed at the UE 504 but passesthrough an obstruction 530 (e.g., vegetation, a building, a hill, adisruptive environment such as clouds or smoke, etc.), which maysignificantly degrade the RF signal. As will be appreciated, althoughthe LOS stream 524 is weaker than the NLOS stream 523, the LOS stream524 will arrive at the UE 504 before the NLOS stream 523 because itfollows a shorter path from the base station 502 to the UE 504.

As noted above, the beam of interest for data communication between abase station (e.g., base station 502) and a UE (e.g., UE 504) is thebeam carrying RF signals that arrives at the UE with the highest signalstrength (e.g., highest RSRP or SINR), whereas the beam of interest forposition estimation is the beam carrying RF signals that excite the LOSpath and that has the highest gain along the LOS path amongst all otherbeams (e.g., beam 514). That is, even if beam 513 (the NLOS beam) wereto weakly excite the LOS path (due to the propagation characteristics ofRF signals, even though not being focused along the LOS path), that weaksignal, if any, of the LOS path of beam 513 may not be as reliablydetectable (compared to that from beam 514), thus leading to greatererror in performing a positioning measurement.

While the beam of interest for data communication and the beam ofinterest for position estimation may be the same beams for somefrequency bands, for other frequency bands, such as mmW, they may not bethe same beams. As such, referring to FIG. 5, where the UE 504 isengaged in a data communication session with the base station 502 (e.g.,where the base station 502 is the serving base station for the UE 504)and not simply attempting to measure reference RF signals transmitted bythe base station 502, the beam of interest for the data communicationsession may be the beam 513, as it is carrying the unobstructed NLOSstream 523. The beam of interest for position estimation, however, wouldbe the beam 514, as it carries the strongest LOS stream 524, despitebeing obstructed.

FIG. 6A is a graph 600A showing the RF channel response at a receiver(e.g., UE 504) over time according to aspects of the disclosure. Underthe channel illustrated in FIG. 6A, the receiver receives a firstcluster of two RF signals on channel taps at time T1, a second clusterof five RF signals on channel taps at time T2, a third cluster of fiveRF signals on channel taps at time T3, and a fourth cluster of four RFsignals on channel taps at time T4. In the example of FIG. 6A, becausethe first cluster of RF signals at time T1 arrives first, it is presumedto be the LOS stream (i.e., the stream arriving over the LOS or theshortest path), and may correspond to the LOS stream 524. The thirdcluster at time T3 is comprised of the strongest RF signals, and maycorrespond to the NLOS stream 523. Seen from the transmitter's side,each cluster of received RF signals may comprise the portion of an RFsignal transmitted at a different angle, and thus each cluster may besaid to have a different angle of departure (AoD) from the transmitter.FIG. 6B is a diagram 600B illustrating this separation of clusters inAoD. The RF signal transmitted in AoD range 602 a may correspond to onecluster (e.g., “Cluster1”) in FIG. 6A, and the RF signal transmitted inAoD range 602 b may correspond to a different cluster (e.g., “Cluster3”)in FIG. 6A. Note that although AoD ranges of the two clusters depictedin FIG. 6B are spatially isolated, AoD ranges of some clusters may alsopartially overlap even though the clusters are separated in time. Forexample, this may arise when two separate buildings at same AoD from thetransmitter reflect the signal towards the receiver. Note that althoughFIG. 6A illustrates clusters of two to five channel taps, as will beappreciated, the clusters may have more or fewer than the illustratednumber of channel taps.

As in the example of FIG. 5, the base station may utilize beamforming totransmit a plurality of beams of RF signals such that one of the beams(e.g., beam 514) is directed at the AoD range 602 a of the first clusterof RF signals, and a different beam (e.g., beam 513) is directed at theAoD range 602 b of the third cluster of RF signals. The signal strengthof clusters in post-beamforming channel response (i.e., the channelresponse when the transmitted RF signal is beamformed instead ofomni-directional) will be scaled by the beam gain along the AoD of theclusters. In that case, the beam of interest for positioning would bethe beam directed at the AoD of the first cluster of RF signals, as theyarrive first, and the beam of interest for data communications may bethe beam directed at the AoD of the third cluster of RF signals, as theyare the strongest.

In general, when transmitting an RF signal, the transmitter does notknow what path it will follow to the receiver (e.g., UE 504) or at whattime it will arrive at the receiver, and therefore transmits the RFsignal on different antenna ports with an equal amount of energy.Alternatively, the transmitter may beamform the RF signal in differentdirections over multiple transmission occasions and obtain measurementfeedback from the receiver to explicitly or implicitly determine radiopaths.

Note that although the techniques disclosed herein have generally beendescribed in terms of transmissions from a base station to a UE, as willbe appreciated, they are equally applicable to transmissions from a UEto a base station where the UE is capable of MIMO operation and/orbeamforming. Also, while beamforming is generally described above incontext with transmit beamforming, receive beamforming may also be usedin conjunction with the above-noted transmit beamforming in certainembodiments.

As discussed above, in some frequency bands, the shortest path (whichmay, as noted above, be a LOS path or the shortest NLOS path) may beweaker than an alternative longer (NLOS) path (over which the RF signalarrives later due to propagation delay). Thus, where a transmitter usesbeamforming to transmit RF signals, the beam of interest for datacommunication—the beam carrying the strongest RF signals—may bedifferent from the beam of interest for position estimation—the beamcarrying the RF signals that excite the shortest detectable path. Assuch, it would be beneficial for the receiver to identify and report thebeam of interest for position estimation to the transmitter to enablethe transmitter to subsequently modify the set of transmitted beams toassist the receiver to perform a position estimation.

FIG. 7 illustrates an example scenario for OTDOA based positionestimating technique. OTDOA is a multilateration methodology in which aUE measures the time of arrival (TOA) of downlink reference signals (DLRS) received from multiple cells (base stations, eNBs, gNBs, etc.). TheTOAs from several neighboring cells are subtracted from a TOA of areference cell (eNB₁ in FIG. 7) to form OTDOAs. Geometrically, each time(or range) difference determines a hyperbola, and the point at whichthese hyperbolas intersect is the estimated UE location.

To estimate a two-dimensional (2D) (x, y or latitude, longitude)location of the UE, a minimum of three timing measurements fromgeographically dispersed cells are necessary. In FIG. 7, the UE measuresthree TOA's τ₁, τ₂, and τ₃ corresponding to the positioning referencesignals (PRSs) transmitted from cells eNB₁, eNB₂, and eNB₃. Assumingthat eNB₁ is the reference cell, then the two OTDOAs t_(2,1)=τ₂−τ₁ andτ_(3,1)=τ₃−τ₁ are formed by the UE. Each TOA measurements τ_(i) can havesome amount of error/uncertainty, and the hyperbolas include some widthillustrating the measurement uncertainty. The estimated UE location isthe intersection area of the hyperbolas.

The UE determines received signal time differences (RSTDs). RSTD is thetime difference between PRSs from a cell i and from the reference cellmeasured at the UE. RSTD calculation is shown in equation 1.

$\begin{matrix}{{RSTD}_{i,1} = {\frac{\sqrt{\left( {x_{t} - x_{i}} \right)^{2} + \left( {y_{t} - y_{i}} \right)^{2}}}{c} - \frac{\sqrt{\left( {x_{t} - x_{1}} \right)^{2} + \left( {y_{t} - y_{1}} \right)^{2}}}{c} + \left( {T_{i -}T_{1}} \right) + \left( {n_{i -}n_{1}} \right)}} & (1)\end{matrix}$

In equation 1, (T_(i)−T₁) is the transmit time offset between cell i andthe reference cell (also referred to as Real Time Differences (RTDs)),n_(i) and n₁ are measurement errors, and c is the speed of light.

Transmit beamforming (TX BF) at the cell and/or receive beamforming atthe UE can enable increased precision at the cell edge. Also, beamrefinements can also leverage channel reciprocity procedures in newradio (NR). Uplink time difference of arrival (UTDOA) technique issimilar to OTDOA technique except that the measurements are based onuplink reference signals from the UE.

FIG. 8 illustrates an example scenario for utilizing beam sweeping forpositioning estimation. In particular, Tx beam sweeping for positioningreference signals (PRSs), e.g., Tx beam sweeping at gNB, is illustrated.In this instance, it is assumed that the network is configured withbeamformed PRSs. Multiple instances of PRSs allow for sweeping acrossall angle of departures (AoDs) for a cell at full transmit power (TxPwr)per beam. FIG. 8 illustrates a cell transmitting PRS on beam 1 at time1, transmitting the PRS on beam 2 at time 2, and so on. Each of one ormore cells of the network may transmit its own PRSs at different timeson different beams.

The UE monitors all cells configured to the send PRSs across allinstances. In particular, the UE determines channel energy responses(CERs) based on the received PRSs. The CERs are then pruned across allcells based on some quality metrics. The CERs are used to estimate theTOAs by finding the earliest peak of the PRSs. The UE may need severalinstances to see sufficient number of cells for estimating the positionof the UE. The TOA estimates can be used to estimate the UE position.UE-based estimation is when the UE itself can estimate the position. TheUE-based estimation is possible if a base station almanac (BSA) isprovided to the UE. UE-assisted estimation is when the UE reports theTOA related measurements (e.g., OTDOA, RSTDs, etc.) to the network,e.g., to the location server, and the network estimations the UE'sposition.

In estimating the TOA from the CER, a first arrival path, i.e., the LOSpath, is determined using noise-related quality thresholding forspurious local peaks. A TOA estimate is chosen such that it is theearliest local maximum of the CER such that 1) it is at least somethreshold X dB higher than the median of the CER, and 2) it is at mostsome threshold Y dB lower than the main peak.

FIG. 9 illustrates an example flow for position estimation. In anaspect, the memory 360 of the UE 350 in FIG. 3A may be an example of acomputer-readable medium that stores computer executable instructions toperform the flow of FIG. 9. In another aspect, means to perform the flowof FIG. 9 may comprise one or more of the TX processor 368, thecontroller/processor 358, the memory 360, the channel estimator 358, theRX processor 356, the transceiver 354 of the UE 350.

As seen in FIG. 9, the UE estimates the CERs from the PRSs transmittedfrom the cells. The TOAs are then estimated through determining theearliest local maximum CERs. The gathered estimated TOAs are then prunedto derive the TDOA vector, which is then used to estimate the position(for UE-based) or is reported back to the network (for UE-assisted).

Note that even at relatively high SINRs, there are occasions in whichthe TOA is wrongly estimated. One way to improve positioning accuracy isto select TOAs estimated from PRSs transmitted from geographicallydispersed cells. In an aspect, TOA sorting and pruning techniques can beused to improve positioning accuracy by selecting the TOAs from thegeographically dispersed cells.

FIG. 10 illustrates an example flow for selecting the TOAs to improvepositioning accuracy. In an aspect, the memory 360 of the UE 350 in FIG.3A may be an example of a computer-readable medium that stores computerexecutable instructions to perform the flow of FIG. 10. In anotheraspect, means to perform the flow of FIG. 10 may comprise one or more ofthe TX processor 368, the controller/processor 358, the memory 360, thechannel estimator 358, the RX processor 356, the transceiver 354 of theUE 350.

As seen in FIG. 10, the UE can sort the TOAs based on one or morequality metrics of the corresponding CERs. SINR (including SNR) is oneexample of a quality metric. Another example is the median/TOA-peakratio. Yet another is the median/main peak ratio. The UE may then prunethe TOAs based on the quality metrics while at the same time, ensuringthat a sufficient number of geographically cells are represented in theTDOA vector. In other words, the quality of the received PRS is not thesole criteria in selecting the TOAs for pruning. Rather, locations ofthe cells are also taken into account when choosing the TOAs.

FIG. 11 illustrates a scenario for pruning the TOAs according to one ormore aspects. In FIG. 11, assume that cells 1 and 2 are co-sited, i.e.,at the same site. Also assume that based on measurements, the UE hasdetermined that the qualities of the PRSs are in order from best toworst are from cell 1, cell 2, cell3, and cell 4. Recall that toestimate a 2D position of the UE, at least three TOA measurements arenecessary. If the TOAs are chosen purely based on the quality metrics,then the three TOAs selected would be the TOAs of cells 1, 2, and 3.However, the TOAs of cells 1, 2, and 3 would be insufficient since cells1 and 2 are co-sited meaning that the TOAs of cells 1 and 2 areeffectively the same. In this instance, the TOA of cell 2 (or cell 1)may be pruned and the TOA of cell 4 may be included assuming that theTOA of cell 4 meets the quality metric requirements.

Of course, it is possible that more than the minimum number of TOAsselected. For example, the TOAs of both cells 1 and 2 may be included aslong as the TOAs of cells 3 and 4 are also included in the TDOA vector.That is, in an aspect, the TOAs may be pruned so as to ensure thatsufficient number of geographically dispersed cells is represented inthe pruned TOAs (e.g., at least three non-co-sited cells for 2Dpositioning, at least four non-co-sited cells for 3D positioning). Aswill be made clear further below, whether co-sited attribute is but oneof several attributes that may be considered in pruning the TOAs.

Referring back to FIG. 10, from the pruned TOAs, the UE may derive atime difference of arrival (TDOA) vector. For example, the TOA with thehighest quality metric may be identified as the reference TOA, and theRSTDs of other cells in the TDOA vector may be calculated in relation tothe reference TOA (e.g., see equation (1)).

The UE may be equipped to prune the TOAs as described above when thenetwork informs the UE with location attributes of the cells. In anaspect, these location attributes or simply “attributes” are relativeattributes, i.e., relative to one another. That is, the signaledattributes may not include any absolute location information of thecells such as the x, y, z coordinates of the cells. Of course, theactual x, y, z coordinates are known to the location server.

The following are some (not necessarily all) of the attributes of thecells that the UE may be informed of—a co-site attribute, a lineattribute, an area boundary attribute, a height attribute, a heightboundary attribute, and a plane attribute. When a group of cells (e.g.,two or more cells) have the same co-site attribute, the member cells ofthe group are co-sited. When a group of cells (e.g., three or morecells) have the same line attribute, the member cells are on a sameline. For example, the member cells may be on a line parallel to a traintrack. When a group of cells (e.g., two or more cells) have the samearea boundary attribute, the member cells are all located within athreshold area boundary (e.g., within a threshold distance of eachother). When a group of cells (e.g., two or more cells) have the sameheight attribute, the member cells are all at a same height. When agroup of cells (e.g., two or more cells) have the same height boundaryattribute, the member cells are all within a threshold height boundary(e.g., within a threshold height of each other). When a group of cells(e.g., two or more cells) have the same plane attribute, the membercells are all on a same 2D plane.

The signaling of the attributes from the network can be semi-static, andcan be sent to the UE along with the PRS configuration. In one aspect,the signaling can take the form of collections of PRS IDs in which acommon attribute (co-site, line, area boundary, height, height boundary,plane) is identified with a particular PRS ID. The signaling can beprovided to the UE after the UE makes a request, after the network isconfigured, or when the network configures a maximum size of the TOAs tobe reported. Note that information related to height (e.g., the heightattribute, the height boundary attribute, the plane attribute) can besignaled if the network requires 3D positioning.

The network, e.g., through a network entity such as the location server,may signal to the UE attributes of a plurality of cells. In an aspect,the plurality of cells may be grouped into one or more cell groups, andeach cell group may comprise one or more member cells. Each cell groupmay be associated with one an attribute set comprising one or moreattributes such that all member cells of the cell group have allattributes of the associated attribute set in common.

In one aspect, the PRS ID may include a scrambling ID, and the attributeinformation may be embedded in the scrambling IDs of the PRSs. The UEmay use the scrambling ID of each PRS to identify the cell group towhich the corresponding cell belongs. For example, for a scrambling IDof 16 bits, the last two bits (e.g., bits 1 and 0) may be used for theco-site attribute. In this example, the scrambling IDs of two PRSs havethe same last two bits, then it may be assumed that the twocorresponding cells can are co-sited. Conversely, if the last two bitsare different, then it may be assumed that the two cells are notco-sited, i.e., located at different sites. In this example, the lasttwo bits are mapped to a co-site attribute type. As another example,bits 4-2 may be used for the height attributes. Two cells with samevalues in bits 4-2 may be assumed to be at the same height. Conversely,two cells with different values in bits 4-2 may be assumed to be atdifferent heights. In this example, the bits 4-2 are mapped to a heightattribute type.

Generally, if a specified set of bits of the scrambling ID is the samefor two or more cells, then the same two or more cells belong to, i.e.,are member cells of, a cell group with a configured attribute. It may besaid that the bits of each scrambling ID may be divided into one or moreattribute bit ranges. Each attribute bit range may comprise one or morebits, and may be mapped to an attribute type (e.g., co-site attributetype, line attribute type, area boundary attribute type, heightattribute type, height boundary attribute type, plane attribute type,and so on). For each cell of the plurality of cells, each attribute ofthe cell may be encoded in the attribute bit range of the scrambling IDmapped to the attribute type of the attribute.

In another aspect, the attribute information may be embedded into theRRC configuration. The PRSs may be configured with resource IDs. Also,different resource IDs may be associated with different attributes ofthe cells transmitting the PRSs. For example, the UE may determine thatevery three resource IDs are co-sited. That is, cells transmitting PRSswith resource IDs 0-2 are member cells of a cell group co-sited in onelocation, cells with resource IDs 3-5 are member cells of a cell groupco-sited in another location, and so on. Note that the actual x, y, zcoordinates of the locations need not be provided to the UE.

As another example, the UE may determine that cells with resource IDs10-15 are member cells of a cell group at one height, cells withresource IDs 16-20 are member cells of a cell group at another height,and so on. Again, the actual heights of the cells need not be known tothe UE. However, the network entity may inform the UE that heights ofmember cells among different cell height groups differ from each otherby at least a minimum group height different.

Generally, the plurality of PRSs may include a plurality of resourceIDs. The plurality of resource IDs may be grouped into one or moreresource ID groups, and each resource ID group may correspond to a cellgroup. In other words, each resource ID group may correspond to anattribute set of one or more attributes as described above.

In an aspect, the UE may be configured with a default resource IDgrouping to associate different group of resource IDs with differentattribute sets. Alternatively or in addition thereto, the resource IDgroup information may be received from a network entity, such as thelocation server. For example, when the UE receives the resource ID groupinformation from the network, the UE may overwrite any previous resourceID group information.

FIG. 12 illustrates a flow chart of an exemplary method 1200 accordingto an aspect of the disclosure for determining the position of a UE. Themethod 1200 is an example of a UE-assisted technique, and involves theUE and a network entity (e.g., a location server). At 1205, the networkentity sends attribute and cell group information of a plurality ofcells configured to transmit a corresponding plurality of PRSs. Forexample, the information may be sent to the UE along with PRSconfiguration. As mentioned above, the information may be sent as aresult of request from the UE, after a network configuration, or whenthe network configures a maximum size of the TOAs reported back to thenetwork from the UE. In an aspect, means to perform block 1205 mayinclude one or more of the controller/processor 375, the memory 376, theTX processor 316, the transceiver 318, and/or the antenna 320 of thebase station 310 illustrated in FIG. 3A, e.g., when the base station 310serves as the location server. In another aspect, means to perform block1205 may include one or more of the processor 301B, the volatile memory302B, the non-volatile memory 303B, the drive 306 b, and/or the networkaccess ports 304B of the server 300B illustrated in FIG. 3B.

The attribute and cell group information provides at least thefollowing. The plurality cells are grouped into one or more cell groups.Each cell group comprises one or more member cells, in which each membercell is one of the plurality of cells. Each cell group is associatedwith an attribute set comprising one or more attributes (e.g., one ormore of co-site, line, area boundary, height, height boundary, andplane). For each cell group, all member cells of the cell group have allattributes of the associated attribute set in common. For example, if anattribute set of a cell group includes line and height attributes, thenthe UE may assume that all member cells of the cell group are in a sameline and are at a same height. The plurality of PRSs transmittedincludes a plurality of PRS IDs (e.g., scrambling ID, resource ID). Inan aspect, the PRS IDs correspond to the plurality of cells. For eachcell group, the PRS ID of each member cell indicates a membership ofthat cell in the cell group. For example, when scrambling IDs are used,the bit values of the attribute range of the scrambling ID for anattribute is the same for all member cells.

At 1210, the UE receives the attribute and cell group information. In anaspect, means to perform block 1210 may include one or more of thecontroller/processor 359, the memory 360, the RX processor 356, thetransceiver 354, and/or the antenna 352 of the UE 350 illustrated inFIG. 3.

At 1215, the network entity can configure the plurality of cells totransmit a plurality of PRSs. In an aspect, means to perform block 1215may include one or more of the controller/processor 375 and/or thememory 376 of the base station 310 illustrated in FIG. 3A, e.g., whenthe base station 310 serves as the location server. In another aspect,means to perform block 1215 may include one or more of the processor301B, the volatile memory 302B, the non-volatile memory 303B, and/or thedrive 306 b of the server 300B illustrated in FIG. 3B.

At 1220, the UE receives the plurality of PRSs from the plurality ofcells. In an aspect, means to perform block 1220 may include one or moreof the controller/processor 359, the memory 360, the RX processor 356,the transceiver 354, and/or the antenna 352 of the UE 350 illustrated inFIG. 3.

At 1230, the UE detects a plurality of TOAs of the received plurality ofPRSs. For example, for each PRS, the corresponding TOA may be chosensuch that it is the earliest local maximum of the CER meeting thethreshold requirements (e.g., at least some threshold dB higher than themedian of the CER, and no more than some threshold dB lower than themain peak of the CER). In an aspect, means to perform block 1220 mayinclude one or more of the controller/processor 359 and/or the memory360 of the UE 350 illustrated in FIG. 3.

At 1240, the UE prunes the plurality of TOAs based on the plurality ofPRSs. For example, the UE can sort the TOAs based on one or more qualitymetrics (e.g., estimated SINR or SNR, median/TOA-peak ratio, median/mainpeak ratio, etc.). Then the sorted TOAs may be pruned. In an aspect,means to perform block 1240 may include one or more of thecontroller/processor 359 and/or the memory 360 of the UE 350 illustratedin FIG. 3.

At 1250, the TDOA vector may be derived from the pruned TOAs. In anaspect, means to perform block 1250 may include one or more of thecontroller/processor 359 and/or the memory 360 of the UE 350 illustratedin FIG. 3. The UE sorts the TOAs such that the resulting TDOA vectorinclude TOA related measurements (e.g., TOAs, RSTDs) of multiple cellsin which each cell represented in the TDOA vector is a cell of theplurality of cells.

Also, the cells represented in the TDOA vector are sufficient todetermine a position of the UE in at least 2D. For example, the TOApruning may be such that the TDOA vector includes TOA relatedmeasurements from at least three cells that are NOT co-sited with eachother. In other words, the TDOA should represent at least three cellswith different co-site attributes. This ensures that TOAs of PRSs from asufficient number of geographically dispersed cells are taken intoaccount for 2D position determination. Of course, if the network allows,more than three TOA related measurements may be included. Additionalmeasurements can help to reduce the uncertainties.

If cell groups with different line attributes are included, then in anaspect, positioning accuracy may be enhanced by pruning the TOAs suchthat the TDOA vector represents multiple—at least two—cells withdifferent line attributes. If cell groups with different area boundaryattributes are included, then in an aspect, positioning accuracy may beenhanced by pruning the TOAs such that the TDOA vector representsmultiple—at least two—cells with different area boundary attributes.

If the UE position in 3D is desired, then TDOA should include TOArelated measurements from at least four geographically dispersed cells.In an embodiment, at least four cells that are not co-sited with eachother may be represented in the TDOA vector. In another embodiment, twoof the cells may be within a same boundary area, but at differentheights. Of course, it is preferable that the cells are in differentboundary areas and at different heights. That is, if cell groups withdifferent height attributes are included, then in an aspect, positioningaccuracy may be enhanced by pruning the TOAs such that the TDOA vectorrepresents multiple—at least two—cells with different height attributes.Also, if cell groups with different plane attributes are included, thenin an aspect, positioning accuracy may be enhanced by pruning the TOAssuch that the TDOA vector represents multiple—at least two—cells withdifferent plane attributes. Again, if the network allows, more than fourTOA related measurements may be included to reduce the uncertainties.

At 1260, the UE sends the TDOA vector to the network entity, e.g., thelocation server. In an aspect, means to perform block 1260 may includeone or more of the controller/processor 359, the memory 360, the TXprocessor 368, the transceiver 354, and/or the antenna 352 of the UE 350illustrated in FIG. 3.

At 1265, the network entity, e.g., the location server, receives theTDOA vector. In an aspect, means to perform block 1265 may include oneor more of the controller/processor 375, the memory 376, the RXprocessor 370, the transceiver 318, and/or the antenna 320 of the basestation 310 illustrated in FIG. 3A, e.g., when the base station 310serves as the location server. In another aspect, means to perform block1265 may include one or more of the processor 301B, the volatile memory302B, the non-volatile memory 303B, the drive 306 b, and/or the networkaccess ports 304B of the server 300B illustrated in FIG. 3B.

At 1275, since the location server is aware of the x, y, z coordinatesof the plurality of cells, at 1275, the location server determines orotherwise estimates the UE position based on the TDOA vector. In anaspect, means to perform block 1275 may include one or more of thecontroller/processor 375, the memory 376, the RX processor 370, thetransceiver 318, and/or the antenna 320 of the base station 310illustrated in FIG. 3A, e.g., when the base station 310 serves as thelocation server. In another aspect, means to perform block 1275 mayinclude one or more of the processor 301B, the volatile memory 302B, thenon-volatile memory 303B, the drive 306 b, and/or the network accessports 304B of the server 300B illustrated in FIG. 3B.

In an aspect, the memory 376 of the base station 310 in FIG. 3A may bean example of a computer-readable medium that stores computer executableinstructions for one or more of the TX processor 316, thecontroller/processor 375, the channel estimator 374, and/or the RXprocessor 370 of the base station 310 to perform blocks 1205, 1215, 1265and 1275 of the method 1200 when the base station 310 serves as thelocation server. In another aspect, the volatile memory 302B, thenonvolatile memory 303B, and/or the disc drive 304B of the server 300Bmay be examples of computer-readable medium that stores computerexecutable instructions for one or more of the processor 301B and/or thenetwork access ports 304B of the server 300B to perform blocks 1205,1215, 1265 and 1275 of the method 1200.

In yet another aspect, the memory 360 of the UE 350 in FIG. 3A may be anexample of a computer-readable medium that stores computer executableinstructions for one or more of the TX processor 368, thecontroller/processor 358, the channel estimator 358, and/or the RXprocessor 356 of the UE 350 to perform blocks 1210, 1220, 1230, 1240,1250 and 1260 the method 1200.

Those skilled in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those skilled in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted to departfrom the scope of the various aspects described herein.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or other suchconfigurations).

The methods, sequences, and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in Random Access Memory (RAM), flashmemory, Read-Only Memory (ROM), Erasable Programmable ROM (EPROM),Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, aremovable disk, a CD-ROM, or any other form of non-transitorycomputer-readable medium known in the art. An exemplary non-transitorycomputer-readable medium may be coupled to the processor such that theprocessor can read information from, and write information to, thenon-transitory computer-readable medium. In the alternative, thenon-transitory computer-readable medium may be integral to theprocessor. The processor and the non-transitory computer-readable mediummay reside in an ASIC. The ASIC may reside in a user device (e.g., a UE)or a base station. In the alternative, the processor and thenon-transitory computer-readable medium may be discrete components in auser device or base station.

In one or more exemplary aspects, the functions described herein may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on a non-transitorycomputer-readable medium. Computer-readable media may include storagemedia and/or communication media including any non-transitory mediumthat may facilitate transferring a computer program from one place toanother. A storage media may be any available media that can be accessedby a computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code in the form of instructions or data structures and that canbe accessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if the software is transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave, then the coaxial cable, fiber opticcable, twisted pair, DSL, or wireless technologies such as infrared,radio, and microwave are included in the definition of a medium. Theterm disk and disc, which may be used interchangeably herein, includes aCompact Disk (CD), laser disc, optical disk, Digital Video Disk (DVD),floppy disk, and Blu-ray discs, which usually reproduce datamagnetically and/or optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects, those skilledin the art will appreciate that various changes and modifications couldbe made herein without departing from the scope of the disclosure asdefined by the appended claims. Furthermore, in accordance with thevarious illustrative aspects described herein, those skilled in the artwill appreciate that the functions, steps, and/or actions in any methodsdescribed above and/or recited in any method claims appended hereto neednot be performed in any particular order. Further still, to the extentthat any elements are described above or recited in the appended claimsin a singular form, those skilled in the art will appreciate thatsingular form(s) contemplate the plural as well unless limitation to thesingular form(s) is explicitly stated.

What is claimed is:
 1. A method of a user equipment (UE), comprising: receiving a plurality of positioning reference signals (PRS) from a plurality of cells, the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with an attribute set comprising one or more attributes, for each cell group, all member cells having all attributes of the associated attribute set in common, the plurality of PRSs including a plurality of PRS IDs, and for each cell group, a PRS ID of each member cell indicating a membership of that member cell in that cell group; detecting a plurality of time of arrivals (TOA) of the plurality of PRSs; deriving a time difference of arrival (TDOA) vector from the plurality of TOAs; and sending the TDOA vector to a network entity, wherein the TDOA vector includes multiple TOA related measurements of multiple cells.
 2. The method of claim 1, wherein each cell associated with a TOA measurement in the TDOA vector is a cell of the plurality of cells, and wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine a position of the UE at least in 2D.
 3. The method of claim 1, wherein for each cell group, all attributes of the associated attribute set are relative attributes.
 4. The method of claim 1, further comprising: pruning the plurality of TOAs based on the plurality of PRSs, wherein the TDOA vector is derived from the pruned TOAs.
 5. The method of claim 4, wherein pruning the plurality of TOAs comprise: sorting the TOAs based on one or more quality metrics; and pruning the sorted TOAs.
 6. The method of claim 4, wherein at least one cell group, at least one attribute of the associated attribute set is one of: a co-site attribute indicating that all member cells of the at least one cell group are co-sited, a line attribute indicating that all member cells of the at least one cell group are in a line, and an area boundary attribute indicating that all member cells of the at least one cell group are within a threshold area boundary.
 7. The method of claim 6, wherein the plurality of TOAs are pruned so that the TDOA vector represents any one or more of: at least three cells with different co-site attributes, at least two cells with different line attributes, and at least two cells with different area boundary attributes.
 8. The method of claim 4, wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine a position of the UE in 3D, and wherein for at least one cell group, at least one attribute of the associated attribute set is one of: a height attribute indicating that heights of all member cells of the at least one cell group are within a threshold height difference of each other, and a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane.
 9. The method of claim 8, wherein the plurality of TOAs are pruned so that the TDOA vector represents one or both of: at least two cells with different height attributes, and at least two cells with different plane attributes.
 10. The method of claim 8, wherein heights of member cells of one cell group differs from heights of member cells of another cell group by at least a minimum group height difference.
 11. The method of claim 1, wherein the plurality of PRS IDs includes a plurality of scrambling IDs, each scrambling ID corresponding to one of the plurality of cells.
 12. The method of claim 11, wherein bits of each scrambling ID are divided into one or more attribute bit ranges, each attribute bit range comprising one or more bits, each attribute bit range being mapped to an attribute type of one or more attribute types, wherein for each cell, each attribute of that cell is encoded in the attribute bit range of the scrambling ID mapped to the attribute type of that attribute, and wherein the method further comprises: receiving a scrambling ID information from the network entity, the scrambling ID information specifying a mapping between the one or more attribute bit ranges and the one or more attribute types.
 13. The method of claim 1, wherein the plurality of PRS IDs includes a plurality of resource IDs, each resource ID corresponding to one of the plurality of cells.
 14. The method of claim 13, wherein the plurality of resource IDs are grouped into one or more resource ID groups, each resource ID group corresponding to a cell group of the one or more cell groups, and wherein the method further comprises one or both of: retrieving a default resource ID group information configured within the UE, the default resource ID group information identifying the one or more resource ID groups; and receiving a resource ID group information from the network entity, the resource ID group information identifying the one or more resource ID groups.
 15. A method of a network entity, comprising: configuring a plurality of cells to transmit a plurality of positioning reference signals (PRS) to a user equipment (UE), the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with an attribute set comprising one or more attributes, for each cell group, all member cells having all attributes of the associated attribute set in common, the plurality of PRSs including a plurality of PRS IDs, and for each cell group, a PRS ID of each member cell indicating a membership of that member cell in that cell group; receiving a time difference of arrival (TDOA) vector from the UE; and determining a position of the UE based on the TDOA vector, wherein the TDOA vector includes multiple TOA related measurements of multiple cells, wherein each cell associated with a TOA measurement in the TDOA vector is a cell of the plurality of cells, and wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine a position of the UE at least in 2D.
 16. The method of claim 15, wherein for each cell group, all attributes of the associated attribute set are relative attributes.
 17. The method of claim 15, wherein at least one cell group, at least one attribute of the associated attribute set is one of: a co-site attribute indicating that all member cells of the at least one cell group are co-sited, a line attribute indicating that all member cells of the at least one cell group are in a line, and an area boundary attribute indicating that all member cells of the at least one cell group are within a threshold area boundary.
 18. The method of claim 17, wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine the position of the UE in 3D, and wherein for at least one cell group, at least one attribute of the associated attribute set is one of: a height attribute indicating that heights of all member cells of the at least one cell group are within a threshold height difference of each other, and a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane.
 19. The method of claim 18, wherein heights of member cells of one cell group differs from heights of member cells of another cell group by at least a minimum group height difference.
 20. The method of claim 15, wherein the plurality of PRS IDs includes a plurality of scrambling IDs, each scrambling ID corresponding to one of the plurality of cells.
 21. The method of claim 20, wherein bits of each scrambling ID are divided into one or more attribute bit ranges, each attribute bit range comprising one or more bits, each attribute bit range being mapped to an attribute type of one or more attribute types, wherein for each cell, each attribute of that cell is encoded in the attribute bit range of the scrambling ID mapped to the attribute type of that attribute, and wherein the method further comprises: sending a scrambling ID information to the UE, the scrambling ID information specifying a mapping between the one or more attribute bit ranges and the one or more attribute types.
 22. The method of claim 15, wherein the plurality of PRS IDs includes a plurality of resource IDs, each resource ID corresponding to one of the plurality of cells.
 23. The method of claim 22, wherein the plurality of resource IDs are grouped into one or more resource ID groups, each resource ID group corresponding to a cell group of the one or more cell groups, and wherein the method further comprises: transmitting a resource ID group information to the UE, the resource ID group information identifying the one or more resource ID groups.
 24. The method of claim 22, wherein the plurality of resource IDs are ordered such that between any pair of a first cell group and a second cell group, resource IDs of all member cells of the first cell group are less than resource IDs of all member cells of the second cell group.
 25. A user equipment (UE), comprising: a memory; a transceiver; and a processor coupled to the memory and the transceiver, wherein the processor, the memory, and the transceiver are configured to: receive a plurality of positioning reference signals (PRS) from a plurality of cells, the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with an attribute set comprising one or more attributes, for each cell group, all member cells having all attributes of the associated attribute set in common, the plurality of PRSs including a plurality of PRS IDs, and for each cell group, a PRS ID of each member cell indicating a membership of that member cell in that cell group; detect a plurality of time of arrivals (TOA) of the plurality of PRSs; derive a time difference of arrival (TDOA) vector from the plurality of TOAs; and send the TDOA vector to a network entity, and wherein the TDOA vector includes multiple TOA related measurements of multiple cells.
 26. The UE of claim 25, wherein the processor, the memory, and the transceiver are further configured to prune the plurality of TOAs based on the plurality of PRSs, and wherein the TDOA vector is derived from the pruned TOAs.
 27. The UE of claim 26, wherein at least one cell group, at least one attribute of the associated attribute set is one of: a co-site attribute indicating that all member cells of the at least one cell group are co-sited, a line attribute indicating that all member cells of the at least one cell group are in a line, and an area boundary attribute indicating that all member cells of the at least one cell group are within a threshold area boundary, and wherein the processor, the memory, and the transceiver are further configured to prune the plurality of TOAs so that the TDOA vector represents any one or more of: at least three cells with different co-site attributes, at least two cells with different line attributes, and at least two cells with different area boundary attributes.
 28. A network entity, comprising: a memory; a transceiver; and a processor coupled to the memory and the transceiver, wherein the processor, the memory, and the transceiver are configured to: configure a plurality of cells to transmit a plurality of positioning reference signals (PRS) to a user equipment (UE), the plurality of cells being grouped into one or more cell groups, each cell group comprising one or more member cells, each member cell being one of the plurality of cells, each cell group being associated with an attribute set comprising one or more attributes, for each cell group, all member cells having all attributes of the associated attribute set in common, the plurality of PRSs including a plurality of PRS IDs, and for each cell group, a PRS ID of each member cell indicating a membership of that member cell in that cell group; receive a time difference of arrival (TDOA) vector from the UE; and determine a position of the UE based on the TDOA vector, wherein the TDOA vector includes multiple TOA related measurements of multiple cells, wherein each cell associated with a TOA measurement in the TDOA vector is a cell of the plurality of cells, and wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine a position of the UE at least in 2D.
 29. The network entity of claim 28, wherein at least one cell group, at least one attribute of the associated attribute set is one of: a co-site attribute indicating that all member cells of the at least one cell group are co-sited, a line attribute indicating that all member cells of the at least one cell group are in a line, and an area boundary attribute indicating that all member cells of the at least one cell group are within a threshold area boundary.
 30. The network entity of claim 28, wherein the multiple TOA related measurements of the multiple cells included in the TDOA vector are sufficient to determine the position of the UE in 3D, and wherein for at least one cell group, at least one attribute of the associated attribute set is one of: a height attribute indicating that heights of all member cells of the at least one cell group are within a threshold height difference of each other, and a plane attribute indicating that all member cells of the at least one cell group are on a 2D plane. 